Supply, telecommunications, or, for example, computer networks are very difficult for a person to set up by hand once they have grown beyond a certain size. When setting up a network, therefore, the most important consideration is its proper functioning. Once the network has been set up, it can be optimized only at points. In most cases, serious errors can no longer be corrected later on.
Depending on the network type and layout, the widest variety of technologies can be used. Network planners usually have multiple components at their disposal for solving a specific network problem. In the case of telecommunication networks, planners must, among other things, decide whether to use a copper or fiber-optic cable for a specific connection. They must also choose among a wide variety of copper and fiber-optic cable types, all of which vary in terms of their capacities, i.e. transmission rates, number of lines per cable, and maximum possible transmission ranges.
Up to now, network plans for telecommunication networks that will provide coverage for a specific territory have almost always been drawn up manually by experienced network planners. As mentioned above, proper network functioning is the primary concern when drawing up such plans. A network that has been technically optimized and has the most cost-effective layout cannot be set up using the currently known network generation methods.
The conventional method for setting up a telecommunications network is described below, only the most important principles being explained. FIG. 1 shows a territory 1 having individual blocks 2 of houses to be supplied from an exchange (HVK) 7. Blocks 2 have individual users 3, whose phone line requirements 4 are indicated. For purposes of illustration, users 3 in this example do not require any services other than phone lines. Blocks 2 are separated from one another by streets 5 and street intersections 6. As shown in FIG. 2, the network planner has divided territory 1 into areas A through E on the basis of the planning rules established in the past by the carrier and of his store of experience, multiple city blocks, such as A1 and A2, usually being combined into one area. These areas are referred to below as cable distribution areas. The territory is divided into cable distribution areas on the basis of the technology to be used and on the basis of the cable typologies defined in the individual countries. The technology determines the maximum and optimum size of the individual cable distribution areas. In the present example, the network planner has selected, e.g., copper cables, it being possible for one copper cable to have different pairings, such as 10, 20, 50, 75, 100, 150 or 200 copper pairs (CuDA). The copper cable transmission range is sufficient for all users, and the maximum capacity of a cable distributor 8 may be 1 00 copper pairs. The network planner then establishes the locations of cable distributors 8 (KVZA–KVZE) from which the distribution cables (VzK) containing the phone lines are run to individual users 3 along the possible routes, i.e. along the sidewalks and underneath intersections 1 1, as shown in FIG. 3. The telephone lines of the particular area, which are bundled into main cables (Hk) 9 are run directly to exchange 7 from cable distributor 8 of the area. If possible, cables 9 are run along existing cable routes of the other areas in order to reduce the cost of laying cables.
As shown in FIG. 2, area A must be supplied with at least 68 phone lines, area B with at least 72 phone lines, area C with at least 78 phone lines, area D with at least 57 phone lines, and area E with at least 49 phone lines. This means that multiple copper distribution cables, whose utilization depends on the number of copper pairs needed as well as on the cable typology, must be laid in the individual areas. For example, a 20-pair copper distribution cable is needed for one side of a city block A1 and a 50-pair copper distribution cable for the other side of the block. Because of the way the cable distribution areas are divided up, this means that the copper distribution cables have different filling ratios [volumetric efficiencies].
The cable distribution areas formed in this manner must now be connected to exchange (HVK) 7 via main cables (Hk) 9. For example, a main cable with a net capacity of 49 copper pairs is needed to supply cable distribution area E. This means that the main cable having the next higher pairing of 50 copper pairs, which is preferably used, is utilized at a rate of up to 98%. The planner now has two choices for running the main cable of area E to exchange 7. He can run the main cable along routes to a cable distributor in an area A or D situated closer to the exchange in order to run the main cable of area E, along with the main cables of other areas, to a main cable having a higher capacity or a different technology, such as fiber optics. The planner can run the main cable of area E to the cable distributor of either area D or A. In the first case, the main cable leading from exchange 7 to the cable distributor of area D must have a minimum capacity of 106 copper pairs (49 copper pairs in area E and 57 copper pairs in area D). In the second case, the main cable leading from exchange 7 to the cable distributor of area A must have a minimum capacity of 117 copper pairs (49 copper pairs in area E and 68 copper pairs in area D). However, since copper cables having a capacity of 117 or 109 copper pairs are not available, the copper cable with the next higher capacity, i.e. 150 copper pairs, must be selected. Using a 150-pair copper cable, the main cable capacity utilization is 70.67% in the first case and 78% in the second case. To select the optimum network version, the cost of both options must now be calculated. This procedure is repeated for all cable distribution areas.
To provide an optimum network design, all possible combinations must obviously be considered when delimiting the areas and routing the main cables. Selecting the wrong edges for the cable distribution areas in the early stages of network planning produces subsequent errors which cannot be corrected later on.
Because it can also take several weeks to set up a large network manually, and networks often must be set up under extreme time pressure, it is usually not possible to develop alternative solutions when defining the areas. The network is therefore not optimized with a view to efficient network utilization and cost minimization.
As a result, the method described above is not likely to enable the network planner to set up the most cost-effective and profitable network variant.